1. Technical Field
The present disclosure relates to airbag folding methods and airbag apparatuses, and in particular relates to an airbag folding method and an airbag apparatus which are capable of improving storability (package volume).
2. Related Art
A vehicle such as an automobile is equipped with an airbag apparatus for inflating and deploying an airbag in a cabin at the time of an emergency such as collision or sudden deceleration, thereby absorbing impact applied to an occupant. An airbag apparatus generally has: an airbag that is folded in normal times and is inflated and deployed at the time of an emergency; an inflator for supplying pressure gas to the airbag; a retainer for storing the folded airbag and for supporting the inflator; and an airbag cover that holds the retainer and forms an opening through which the airbag is inflated outward.
At the time of collision or sudden deceleration of a vehicle, pressure gas is supplied to the airbag from the inflator to inflate the airbag; then, the airbag cover is split open, and the airbag is inflated and deployed while being inflated outward to the cabin. In particular, when such an airbag apparatus is used for a passenger's seat, the airbag is inflated and deployed to space surrounded by an instrument panel, a wind shield (front window panel) and an occupant.
Known examples of such an airbag include one in which a concave region is formed along a vertical direction in a portion of the airbag, facing an occupant, in an inflated and deployed state in particular (see e.g., JP-A-2010-274901). The concave region extending along the vertical direction defines: a left chamber located forward of a left half of the occupant's body; and a right chamber located forward of a right half of the occupant's body. The concave region is located between the right and left chambers.
However, when the above-mentioned right and left chambers are formed, the airbag has to be widened in a vehicle body width direction at the time of inflation and expansion, thus increasing the airbag in size. Further, sewing of a base cloth of the airbag is complicated in order to form the right and left chambers and to allow the occupant to be also received by the concave region, thus also complicating folding of the airbag when it is stored.
Accordingly, the base cloth is complicated in shape to have a certain thickness even before expansion, and is thus increased in size; as a result, a package volume of the airbag when it is stored is disadvantageously increased.
When the package volume is increased as mentioned above, it is extremely difficult for an installation space of a narrow instrument panel, for example, to store the airbag.